Pressure recorder seal



Patented Oct. 21, 1941- UNITED STATES PATENT OFFICE Standard Oil Companyof Galifornia,

San

Francisco; Calif., a corporation of Delaware Application December 23,1939, Serial No. 310,503

(Cl. l3-.300)

1 Claim.

This invention relates to -fluid pressure recorders of the type that areused in deep wells, such as oil wells, and particularly refers to animproved means for separating the sealing liquid used in contact withthe working parts of the pressure responsive means from thesfluids inthe well or other space in which the pressure measurement is to betaken.

In the drilling and operation of deep oil wells it is desirable andsometimes necessary to make recorded measurements of fluid pressure inthe well bore at varying flow rates and with various arrangements ofpackers, formation testers, tubing valves, chokes and other equipmentused in this art. Typical instruments used for such purposes aredescribed in Patents No. 1,837,222 to Kannenstine, No. 1,955,855 toMarx, and No. 2,078,623 to Wilde. The depths at which these devices areused and the fluid pfessures to be measured thereby have increasedduring the past few years to a point where it becomes increasinglydiflicult to keep the well fluids, under pressures up to 7,500 poundsper square inch, isolated from the pressure transmitting liquids thatare usually employed in contact with the delicate moving parts in thepressure responsive mechanisms. When it is understood that the condition'of use of certain of these recorders limit their outer diameter to notover 1 inches, the necessity for keeping oil, water, sand, gas, and thelike out of the internal parts will be appreciated. Various expedientssuch as screens, flexible metallic bellows, elastic diaphragms or sacks,and the like have been used, but these are necessarily so small thatthey are not always effective, and, in addition, if they should fail bybursting, the interior of the apparatus unavoidably becomes filled withthe well fluid, which renders it inoperative and usually unflt forfurther use.

This invention comprehends broadly an improved means for separating thepressure transmitting liquid usually used in a recorder of this type,from the well fluids whose pressure is to be measured, said meanscomprising a rigid member sliding freely in a carefully machined bore,and preferably with flow control means 'permitting flow outwardly fromthe pressure transmitting liquid to the well fluids, in case ofexpansion of the former by temperature rise or other causes, butpreventing flow in the opposite direction. In this examplefthe machinedbore is open at one end to the well fluid and at the other to thepressure liquid, and the solid member comprises a free piston in thebore with a check valve inthe piston body for the fluid restrainingfunction just mentioned.

It is an object of this invention to providean improved means forsealing the interior parts of a deep well pressure recorder fromabrasive or corrosive fluids in the well bore.

Another object is to provide a sealing means of this character all ofwhose parts are made of rigid material that is not susceptible tofatigue, corrosion or attack by high temperature or the well fluids.

Another object is to provide a sealing means which will provide a.greater displacement volume for pressure transmitting liquid than theexpedients heretofore employed for this purpose.

Another object is to provide a sealing means that will permit escape ofthe pressure transmitting liquid from its system into the well fluids incase of undue expansion of said liquid due to temperature rise or othercauses.

Another object is to provide a sealing means that will act asa safetycheck valve in case of failure of other sealing means in the interior ofcertain types of pressure recorders, to prevent flooding the clockworkand other internal parts by the pressure transmitting fluid or the wellfluids.

Another object is to provide a sealing means ofthis character that isnot only simple and economical to fabricate but also may readily beadapted to-existing pressure recorders, to improve their operatingcharacteristics and insure their internal parts against damage.

These and other objects and advantages will be further apparent from thefollowing description and from the accompanying drawing, which forms apart of this specification and illustrates a preferred embodiment of theinvention as ap plied to a deep well pressure recorder.

In the drawing, Figure 1 is a longitudinal sectional view, to anenlarged scale, of a preferred embodiment of a seal for a pressurerecorder.

Figure 2 is a longitudinal sectional view of the seal of Figure 1 inplace in a recorder of the Standard or Marx type.

Referring to Figure 2, which illustrates the general arrangement, the.pressure recorder there shown comprises a fluid tight casing or housingl0 provided at its upper end with an attachment II for the conventionalwire line l2, and. a fitting l3 for the engagement of an overshotfishing tool in case of breakage of the line I2.

A clockwork l4 in housing I0 is adapted to rotate with a stylus ormarking means 22 which makes a trace or record on chart II as the latterrotates. Chamber 23 into which piston l8. projects and which containsspring 2i is filled with a pressure transmitting liquid 24 which may be.

a refined oil, such as castor oil, and which not only protects the partsjust named from the well fluids but also serves to lubricate and assistin the sealing functions of packing 20. I

A passage 25 lead: from the bottom of fir chamber 23 into the sealingmeans to which this application is particularly directed, and oneexample of which is shown in detail in Figure 1. Desirably housing I isprovided with a downwardly depending hollow, cup-like extension member26 connected thereto by threads 21. An opening 28 in a wall of extension26 permits communication of well fluid pressure from outside the deviceto a second chamber 29 inside of member 26. A tube 30 is secured tohousing III by threads 3| and is open at its upper end to passage 25leading from the pressure fluid chamber 23 of the recording mechanismdescribed above. The bore 32 of tube 30 is accurately machined toreceive a similarly finished rigid piston member 33 which is movablethrough the bore and is closely fitted thereto.

The lower end of bore 32 is preferably provided with an apertured orported plug 34, the latter serving to retain piston 33 in the bore and,in this arrangement also adapted to hold a filter medium 35, which maybe retained in plug 34 by a threaded apertured closure member 36. Theapertures in plug 34 and member 36 permit well fluid or other fluid orliquid from chamber 29 to pass through filter medium 35 and thence intothe bore 32 of tube 30 below piston 33. Under some circumstances suchfiltering of the well fluid may not be necessary, but where sand or mudis present it is usually advantageous.

Desirably some means are provided to permit the pressure liquid 24 toflow outwardly from chamber 23 or bore 32 into the space surrounding theinstrument or into chamber 29, said last named chamber also includingthe space in bore 32 outside of piston 33, in case of excessiveexpansion of the liquid due to temperature changes or other causes. Inthis example such means are located in the piston 33, and take the formof a longitudinal bore 31 in which is mounted a ball valve 38 urgedtoward its seat by spring 39. This permits outward flow of pressureliquid but prevents inward flow of well fluid.

To place the instrument in operation the chart I! is placed in holderl6, the device is inverted and cup member 26 and plug 34 are removed.Filling plug 40, which is provided in body III to communicate with firstchamber 23, is removed and the chamber 23 and bore 32 are pumped full ofa suitable sealing liquid 24, such as castor oil, until piston 33 isforced out of bore 32 and the liquid emerging is free from entrained gasor air bubbles. Filling plug 40 is replaced and piston 33 is forced intobore 32, the valved passage 31 permitting escape of the liquid displacedPlug 34 and cup member 26 are replaced, the instrument returned to itsupright position, and, if desired, that portion of the second chamber 23in cup member 23 is also filled through port 28 with the same sealingliquid as is used in the instrument.

In operation, an increase in pressure on the fluid in which the deviceis immersed is transmitted hydraulically through port 23, chamber 23 andthe passages in member 36, against the lower face of piston 33, forcingthe latter upwardly into bore 32 and imparting the same pressure onsealing liquid 24, which, in turn, forces the movable member, in thisexample axial piston i8, upwardly in bore is against the resistance ofspring 2| into the chamber for the recording or exhibiting element inhousing It.

wardly from bore 32 replaces or fills the space in chamber 23 formerlyoccupied by that portion of the axial piston which has been displaced bythe pressure increase. Piston 33, which acts to separate the liquid 24in bore 32 from whatever fluid may be below thatpiston, serveseffectively to seal the pressure transmitting liquid from the wellfluids which may enter chamber 23 through pressure port 28. Ifthepressure responsive piston packing 20 should fail, pressure transmittingliquid 24 would be forced upwardly into the chart housing, but only toan amount that would be present above piston 33 in bore 32, as thatpiston would stop at the top of bore 32 and prevent complete filling ofthe chart and clock chambers.

Thus it will be appreciated that ilmproved sealing means has beenprovided for-pressure recorders of this character, these means gen-.-erally comprising a bore or passage open at one end to the pressuretransmitting liquid in the device and open at the other end to thesource of fluid pressure to .be measured, with a closely fitted rigidmember slidable in said bore. Desirably, but not necessarily, flowcontrol means are provided selectively to by-pass said member, and inaddition, filter means may be included to protect the bore and memberfrom abrasive materials in the fluid whose pressure is to be determined.Obviously the improvement is not only applicable to the axial pistontype of pressure recorder here described but to the Bourdon tube typeofKannenstine, whose tube, if it should burst, would flood the workingparts with well fluid, as well as those other types in which a pressuretransmitting liquid may be used and in which it is desirable that thesaid liquid be separated from the well fluids.

Although aspecific example has been shown and described, it is apparentthat many changes and modifications could be made in it withoutdeparting from the invention, and it is to be understood that all suchthat fall within the scope of the appended claim are embraced thereby.

I claim:

In a pressure recorder provided with a first chamber, a movable memberat one end of said chamber, said member being connected to an exhibitingelement, a spring for opposing movement of said member, said firstchamber being filled with a sealing liquid for transmitting fluidpressure changes to said member to move the latter, means adjacent saidmember at one end of said chamber for filling it with said sealingliquid, vmeans forming a cylindrical passage leading from the oppositeend of said first chamber to a second chamber communicating with thefluid whose pressure is to be measured, an unattached rigid cylindricalmember filling the bore 01' said passage, said member being freelymovable therein and effective to separate said sealing liquid from fluidentering said passage from said second chamber, and a check valve insaid cylindrical member to permit liquid to flow from said first chamberinto said second chamber during the filling of said first chamher withsealing liquid and at such other times that the pressure in said firstchamber exceeds that in said second chamber, said check valve beingeflective to prevent fluid flow in the opposite direction, said movablemember, first chamber, cylindrical passage and check valve being alignedto promote evacuation of air or fixed gases from the sealing liquid insaid first chamber and said passage during said filling operation.

HUGH B. WEBSTER.

